Acute Exercise Effect On Brain Activity During Task Switching In Healthy Young And Older Adults

PURPOSE: To determine the acute effect of moderate aerobic exercise on task switching performance and its associated brain neural activity in healthy young and older adults METHODS: This is a crossover study enrolling 17 healthy young (8 women and 9 men, 25 ± 2 yr) and 19 older (10 women and 9 men, 62 ± 5 yr) adults. Each participant underwent two experimental conditions (i.e., exercise and control) on separate days in random order. In the exercise condition, participants completed a 30-min moderate-intensity aerobic exercise (60-70% of the age-predicted maximal heart rate) on a motor-driven treadmill. In the control condition, they sat quietly on a chair for 30 min. In both conditions, functional magnetic resonance imaging (fMRI) data were collected during task switching at 3 time points: baseline (before exercise or control condition) and 10 min (post-1) and 30 min (post-2) after intervention. The main outcomes were task switching performance (error rates and reaction times) and the task-related brain neural activity. RESULTS: Error rates and reaction times during task switching improved in both exercise and control conditions over time (p < 0.05), although no significant condition or condition-by-time interaction effects were observed. Both young and older groups showed similar improvements in task performance over time (p > 0.05). fMRI data showed a significant decrease in the task-related brain activity over time in both conditions and age groups (p < 0.001), although no significant interaction effect was observed. No region showed an increase in the task-related brain activity in both conditions and age groups (p > 0.05 for time effect). CONCLUSIONS: Task switching performance improved while the task-related brain neural activity decreased over time in healthy young and older adults, although acute exercise effect was not observed. Our results suggest that task repetition enhanced neurocognitive efficiency (i.e., decreased brain activity coupled with improved cognitive performance), regardless of age groups and acute exercise intervention.